The Vanguard Group discloses this finding in “How America saves 2013: A report on Vanguard 2012 defined contribution plan data.” The report is based on 2012 Vanguard recordkeeping data of more than 1,600 plan sponsors and 3 million plan participants served by the company.

The report shows that plan participants invested the largest percentage of their assets in diversified equity funds in 2012. This is level with that of 2011, but down slightly from the percentages recorded in 2010 and 2009 (43 percent for both years).

Last year, employees also allocated plan assets to the following categories:

“The overall equity allocation is up from 61 percent in 2008, a shift of 5 percentage points, due to the rise in equity markets from the 2008-2009 downturn,” the report states. “The growth of target-date funds in particular is dramatically reshaping investment patterns in DC plans, including increasing equity allocation differences by age and reducing extreme allocations.”

The report adds that nearly all plans offer international equity funds, but only 225 offer separate, emerging market funds. Additionally, one-third of plans feature sector funds, such as technology or health care funds.

At year-end, the survey adds, 84 percent of plans offered target-date funds, reflecting rising interest among employers in this category. Target-date funds automatically reset the asset mix (stocks, bonds, cash equivalents) in a portfolio according to a selected time frame appropriate for an investor.

In 2012, four in 10 plans (44 percent) immediately vested participants in employer-matching contributions. Large plans are slightly more likely (47 percent) to offer immediate vesting of employer-matching contributions.

Smaller plans, the report adds, are more likely to use longer vesting schedules. About one-third of plans (32 percent) with employer-matching contributions use a 5- or 6-year graded vesting schedule. One in four (22 percent) of plan participants has a longer vesting schedule.